NBC’s Concentration, aired for 14 years, 7 months for a total of 3,770 telecasts from August 25, 1958 to March 23, 1973, the longest run of any game show on NBC. The series was hosted by Hugh Downs (pictured above) and later by Bob Clayton (below).For a six-month period from March to September 1969, Ed McMahan hosted the show which was based on the children’s memory game of the same name.